I picked up several while at the yard. They ended up being free. It is a common part and those from at least to 89 fit my 85SD.
by the time you deal with the dealer, you could fnd some at the yard unless you are in the frozen, rusty north.
Other models from that ere fay fit also ie 123, wagon etc. The filler on my floor came off but I was able to make a connector with plywood and a piece of metal from a tin roof that I had lying around.
85SD 240K & stopped counting. Looking for all 3 grey seats to go in my SD (anything from a 126).